1. Field of the Invention
The invention relates to a PM generating apparatus for generating particulate matter (PM) in a gas in order to evaluate an exhaust gas purifying apparatus equipped with DPF, a catalyst, and the like.
2. Background Art
Particulate matter (PM) and toxic substances contained in exhaust gas from various internal combustion engines have a significant effect on human bodies and the environment. The need for preventing emission of particulate matter and toxic substances to the atmosphere is increasing. In particular, the effects of PM and NOx (nitrogen oxide) discharged from diesel engines are serious and regulations prohibiting their emission are reinforced worldwide. For this reason, exhaust gas purifying apparatus equipped with a diesel particulate filter (DPF) for removing PM or a catalyst useful for reducing NOx to nitrogen and water have been investigated and developed. Some high performance exhaust gas purifying apparatus have been introduced into the market.
However, no means for testing the exhaust gas purifying apparatus and accurately and correctly evaluating the performance and durability of such a exhaust gas purifying apparatus has been proposed until now. There are few prior art documents. Although some prior art technologies relating to an evaluation gas feeder (Patent Document 1), a vapor gas feeder (Patent Document 2), and a gas analyzer (Patent Document 3) are known, these technologies have problems such as incapability of adequately imitating actual exhaust gas (see Patent Document 1) and unavailability of a specific means for generating exhaust gas (see Patent Documents 2 and 3).
The prior art technologies are now described. As a means to evaluate the performance and the like of an exhaust gas purifying apparatus, a method of supplying exhaust gas from an actual diesel engine to an exhaust gas purifying apparatus and analyzing the gas processed by the exhaust gas purifying apparatus can be given. A method of carbon powder or PM extracted from actual exhaust gas in a gas phase to produce an imitation exhaust gas imitating the exhaust gas from an actual diesel engine and the like, feeding that gas to an exhaust gas purifying apparatus, and analyzing the gas processed by the exhaust gas purifying apparatus is also known (see Patent Document 1). In addition, a method of generating exhaust gas containing PM by burning gas oil or hydrocarbons and a method of generating exhaust gas containing PM by causing a graphite electrode to spark are also known. It is possible to evaluate the performance and the like of an exhaust gas purifying apparatus using such an exhaust gas (see Patent Document 1).
(Patent Document 1) JP-A-2005-214742
(Patent document 2) JP-A-10-318888
(Patent document 3) JP-A-10-319006